Press with hydraulically operated press plungers



June 28, 1955 STUDLI 2,711,561

PRESS WITH HYDRAULICALLY OPERATED PRESS PLUNGERS Filed Aug. 19, 1952 5 Shets-Sheet 1 FIG/1 IN VE N TOR 5 //0/ .5 5m d/f,

PRESS WITH HYDRAULICALLY OPERATED P'REss PLUNGERS Filed Aug. 19, 1952 H. STUDLI June 28, 1955 5 Sheets-Sheet 2 FIG. 2

' INVENTOR fleasJfad/f,

June 28, 1955 sTU 2,711,561

PRESS WITH HYDRAULICALLY OPERATED PRESS PLUNGERS Filed Aug. 19, 1952 I SYSheetS-Sheet 3 INVEN TOR 1 3o Ala/2.5 Jzua fl,

/ for/7 ey June 28, 1955 H. STUDLI 2,711,561

PRESS WITH HYDRAULICALLY OPERATED PRESS PLUNGERS Filed Aug. 19, 1952 5 Sheets-Sheet 4 INVENTOR! flan: J/u d/f,

June 28, 1955 H. STUDLI 2,711,561

PRESS WITH HYDRAULICALLY OPERATED PRESS PLUNGERS Filed Aug. 19, 1952 s Shets-Sheet 5 INVEN TOR PRESS WITH HYDRAULICALLY OPERATED PRESS PLUNGERS Hans Stiidii, Winterthur-Hard, Switzerland Application August 19, 1952, Serial No. 305,160

13 Claims. (C l. 18--30) This invention relates to presses with hydraulically operated press plungers and more particularly to a press of this kind which comprises a first press plunger of large cross section and short stroke acting in one direction and a second press plunger of smaller cross section and longer stroke acting in opposite direction and as well a pressplate guided on columns, which pressplate is taken along by the second press plunger during a first part of its forward movement and then is locked on the columns in its end position whereupon the press plunger continues its further forward movement. Due to the locking of the pressplate on the columns in its end position, it is attained that the tension acting upon the columns is present from the foundation plate only up to the point of locking of the pressplate, while at presses known so far the whole length of the column is subjected to the mentioned tension. Furthermore all operations requiring a comparatively long stroke and comparatively little power, such as the opening and closing of the mould and the injection of the material may be carried out at this press by the second plunger while the operations, such as for instance the locking of the mould, which require a short travel but a great force may be done. by the first plunger.

The press according to the present invention may be used as die-casting press, and as well as a transfer or Bakelite press, or also as a sheet metal forming press.

The invention is fully disclosed in the following specification of which the accompanying drawings form a part and represent an embodiment of the invention given merely by way of example, and in which:

Fig. 1 is a vertical section through the lower part of a die-casting press, with a press plunger movable in upright direction, along the line I-I of Fig. 4,

Fig. 2 is a side elevation of Fig. 1,

Fig. 3 is a vertical middle section through the upper part of the press,

Fig. 4 is a horizontal section along the line IVIV of Fig. l,

Fig. 5 is a section through a detail part,

Fig. 6 is a horizontal section along the line VIVI of Fig. 1,

Fig. 7 is a section along the line VIIVII of Fig. 4 and as well a side elevation of a rack and guide rail, and

Fig. 8 is a diagrammatic view of the control for the die-casting press.

Referring now to Fig. 1, the illustrated press is provided with a foundation frame 1 carrying a lower cylinder block 2 which by means of four columns 3 is connected with an upper cylinder block 4 (Fig. 3). The latter is closed at its top by a cover 5 to which a conduit 6 is connected for supplying and removing pressure fluid. Another pressure fluid conduit 7 is connected to the lower part of the cylinder block 4. Within said cylinder block a piston 8 is slidably mounted, this piston being in rigid connection with a piston rod 9 which passes through a stufiing box 10 and carries a yoke 11 on which two' rails 12 are suspended. These rails are atent O each provided with an upper threaded portion 13, each such portion carrying a nut 14 lodged between the forked ends of the yoke 11, which ends are provided with bores through which the threaded portions 13 of the rails 12 pass. In this manner, the rails 12 are connected to the yoke 11 and their position with respect to the said yoke may be adjusted by turning the nuts 14. Each rail has a groove 15 having an oblique lower end portion 16 (Fig. 2). A pin 17 mounted in the middle part of a rack 18 which is guided in a slot 19 of a press plate 20 engages each groove 15. A sheet metal cover 21 enclosing the rack 18 is mounted on the press plate 20. Each rail 12 is guided in a groove 22 of the press plate 20 and also by a guiding plate 23 made in two parts attached to said plate 20. The press plate 20 is slidably guided on the four columns 3. These columns have six longitudinal grooves 24 between which there are splines 25 provided with trapezoidal screw threads 26 in the zone which the press plate 20 occupies when in its lowermost. position. Each of the columns 3 is surrounded by an externally threaded sleeve 27 which on its inside has six grooves 28 and six splines 29, the latter being provided with trapezoidal threads (Fig. 5). Externally, each sleeve 27 also is provided with a trapezoidal screw thread, by. means of which it is screwed into a corresponding threaded bore of the press plate 24). In its middle portion, the sleeve 27 moreover is provided with teeth 30 engaging corresponding teeth 31 of the rack 18 (Fig. 4). It is evident that by shifting the rack 18 the threaded sleeve 27 may be rotated so that its threaded splines 23 may be brought into or out of engagement with the screw thread 26 on the splines 25 of the column 3. The press-plate 20 is held by the pin 17 engaging the groove 15 of the rail 12. 'On lowering and raising the press plate 20 the pin 17 lies in the end portion 16 of the groove 15. The pin 17 is connected to the rack 18 and the teeth 31 of the rack 18 engage the teeth 30 of sleeve 27. As the sleeve 27 cannot turn except in the lowermost position of the press plate 20, it is to be understood that on the lowering and raising of the plate 20 the pin 17 cannot leave the end portion 16 and thereby the press plate 20 is positively connected to the rail 12 and the yoke 11 and the piston rod 9, respectively. In the lowermost position of the press plate the sleeve 27 will be turned and the press plate locked. The pin 17 can now leave the end portion 16 and move in the vertical portion of the groove 15.

The upper part 33 of the die is fastened to the press plate 20 by means of screws 32. The injection head 34 rests with its nozzle 35 against the upper die 33 and is fixed to a second press plate 36 by means of screw bolts 37. For retaining the press plate 36 in its position, two screw bolts 38 are linked to the plate 20 by means of hinges 39. These bolts 38 may be swung into slots 40 of the press plate 36 whereupon the plate 36 is pressed downwards by means of nuts 41 so that the injection head 34 is tightly pressed against the upper die 33.

On the press plate 36, the measuring or dosing device (Figs. 2 and 6) for the material to be injected is located. This dosing device comprises a funnel-shaped casing 42 fastened to the plate 36 and at its bottom is provided with a cylindric bore for an ejection piston 43, which latter is guided in a bracket 44 and has two lateral trunnions 45 each of which engages a slotted guide 47 in a one-armed lever 46. The two levers 46 are rigidly mounted on a shaft 48. A lever 59 cooperates with a cam 49 on one of the levers 46; this lever 50 is swingably mounted on the shaft 48 and carries two adjustment screws 51, 52 between which the cam 49 is located. The lever 50 has a collapsible extension part 53 which by means of a spring 54 coacting with a stop is held in the position as shown in Fig. 2 with full lines and as well in the position indicated with dot and dash lines. When the piston rod 9 together with the yoke 11 moves upwards with respect to the dosing device, a stop surface 55 of the yoke acts upon the free end of the extension part 53, whereby the lever 58 is swung upwards. Hereby the ejection piston 43 by means of the levers 46 is moved forward and thus delivers a certain amount of moulding material into the funnel 56 (Fig. l) disposed upon the injection head 34. In the upper part of the injection head 34- a piston 57 is located which extends underneath the yoke 11 and forms an extension of the piston rod 9.

The lower die 58 rests upon a plunger 59, which is located within a cylindrical boring 68 of the lower cylinder block 2. The lower moulding die 58 is provided with an ejector 61 arranged on a support rod 62 traversing a recess 63 of the lower mould '8 and resting each with each end upon a cross bar 64. These cross bars 64 are fastened to the lower ends of connecting rods 65, passing through eyes 66 of the pressplate and carrying on their top ends nuts 67.

At the lower'end of the left-sided rail 12 an obliquely rising surface-63 (Figs. 1 and 8) is formed with which a roll 69 coacts which roll is journalled on the free end of a lever arm 70 secured to the top end of arod 71. At the lower end of this rod 71 a lever arm 72 is attached, the free end of which engages a slot 73 of the one arm 74 of a cranked lever 74, 75 being hingedly journalled at 76. The other arm 75 of the cranked lever cooperates with a two-armed latch 77, 78, which at 79 is linked to a rod 8! of a slide valve 81. A spring 82 acts upon the latch 77 73 and one arm 78 of the latter cooperates with a stop 83, being disposed on a rod 84 of a slide valve 85. The two slide valves 81 and 85 are located within a control block 86. A spring 87 acts upon the slide valve 81, which spring with its one end bears against a flange 89 provided on the rod 88 of the slide valve 81 and with its other end bears against a cover disc 90 secured on the control block. The slide valve 81 cooperates with a conduit 91, being connected with a supply conduit for a pressure fluid, and with a conduit 93 being connected with a conduit 94 and as well with a conduit 95 which is connected with a back flow conduit 96. Furthermore a conduit 97 leads to a safety valve 98. The tension of the spring 99 acting upon the valve needle 98 may be adjusted by means of a regulating member 180 so that the valve 98 opens at a certain overpressure. A conduit 1191 leads from the safety valve to the slide valve 85 to which also a back flow conduit102is connected. A control valve 183 is further connected to the conduit 97, which valve through a conduit 194 is connected with a pressure conduit 105. A spring 167 acts upon the valve rod 196 of the valve 193, which spring tends to press the valve into closure position. Furthermore an adjusting screw 189 attached to a lever arm 188 coacts with the end of the valve rod 186. The leverarm 108 is mounted on a control shaft 110. Another lever arm 111 carried on the control shaft is provided on its end with an eye through which a rod 112 passes which hangs in an eye of a projection 29 of the pressplate 20. Said rod 112 being provided with a nut 113 such that at an up ward movement of the plate 20 the rod 112 is taken along and at the uppermost position of the plate 29 the nut 113 acts upon the lever arm 111 and rotates it in clockwise direction. The control shaft 110 moreover carries a lever 114 actuated by hand and another lever arm 1 15 hingedly connected with the rod 116 of a slide valve 117, which is disposed in a cylinder block 118. Within this block 118 a safety valve 119 is disposed, the valve needle of which is loaded by a spring 120 adjustable through a threaded regulating member 121. The pressure fluid is supplied by the conduit 9% and according to the posi tion of the slide valve 117 isled either through the conduit 6 to the chamber above the piston 8 or through the conduit 7 to the space underneath the piston 8. The

. ing set 127 to the pressure fluid reservoir.

conduit 7 is also led through a control case 122 containing two spring controlled pressure valves 123, 124. The numeral 125 designates a back flow conduit leading through a cooling set 127 driven by a motor 126 and the numerals 128, 129, 130 designate further back flow conduits. A motor 131 drives a pump 132 for pressure fluid, which pump is connected with a suction conduit 133 and a delivery conduit 92.

The operation of the described die-casting machine is as follows:

Assuming, the upper moulding die 33 together with the press plate 20 and the actuating piston 8 be in the uppermost position, as illustrated in Fig. 8, and the injection head 34 has been supplied with moulding material durin the preceding upwards stroke; if now the manually operated lever 114 is shifted out of its middle or rest position M into the press position P for downstroke, the lever arm 115 and the rod 116 of the slide valve 117 by the intermediary of the shaft 110 are drawn upwards. The pressure fluid now takes the following course: from the pump 132 through the delivery conduit 92, the conduits 91 and 93, the conduit 94 to the cylinder block 118 and from the latter through the conduit 6 to the cylinder 4 into the chamber above the piston 8. The piston 8 is moved downwards, whereby the pressure fluid situated below the piston flows back through the conduit 7 into the control case 122 and over the springcontrolled pressure valve 123 and the conduit 129 flows back to the oil reservoir. The press plate 20 suspended on the rails 12 by means of the pins 17 is at the same time lowered until it comes to rest upon flanges of the columns 3. At the further downward movement of the piston 8 and the rails 12 the pin 17 due to its engagement with the groove 15 of the rail 12 comes out of the oblique end portion 16 into the straight part of the groove, whereby it is shifted sidewise and in doing so takes along the rack 18. The shifting of the racks 18 causes a rotation of the threaded sleeves 27 by approximately 30", whereby the threaded splines 29 of the sleeve 27 come into engagement with the trapezoidal threads 26 of the splines 25 of the columns 3, thus locking the press plate 20 with the columns 3. During this locking operation of the press plate 20 the obliquely rising surface 68 of the one rail 12 acts upon the roll 69 of a lever arm 70 whereby this lever arm and by this the shaft 71 is rotated somewhat. By means of the lever arm 72 the cranked lever 74, 75 is thus rotated and the rod ofthe slide valve 81 is lifted by the end of the lever arm 75 by means of the two-armed latch 77, 78 and the rod 80. Hereby the conduit 93 is closed and the pressure fluid supply to the upper side of the piston 8 is interrupted, so that the movement of the pitson is halted. Furthermore the conduit 91 is connected with the conduit 97 whereby the pressure fluid flows from the pump 132 through conduit 92, conduit 91, conduit 97, valve 103 and conduit 105 into the press cylinder 60 underneath of the plunger 59. This plunger 59 has a large diameter so that a great force forclosing the moulding die is exerted upon the lower moulding die 58. As soon as the required pressure is reached in the press cylinder 60, the safety valve 98 adjusted for this pressure opens, whereby the pressure fluid arrives through the conduit 161 to the upperside of the slide valve 85 forcing it downwards. In doing so the stop 83 unlatches the twoarmed latch 77 78 so that the slide valve 81 is again pulled down by'the spring 87. The conduit 91 is again connected with the conduit 93, so that the piston 8 is moved further downwards by the pressure fluid. Hereby the moulding material is injected into the die by means of the injection piston located underneath the yoke 11. When the required injection pressure is attained, the safety valve 119adjusted for this pressure opens and the pressure fluid flows back through the conduit 125 and thev cool- After a certain time which is required in order to allow the material injected into the, die to harden, the hand operated lever 114 is reversed to its backward position R for the upwards stroke. The adjusting screw 109 present on the lever arm 108 now acts upon the upper end of the valve rod 106 whereby the valve 103 is opened. Thereby the pressure fluid present in the cylinder 60 flows back through the conduits 105 104, 97, 95 and 96 to the pressure fluid reservoir, so that the locked die is free from pressure. Furthermore at the reversing of the lever 114 to the position R for back respectively upwards movement of the upper press piston by means of the lever arm 115 and the rod 116, the reversing slide valve 117 is moved downwards. The pressure fluid flows now from the conduit 94 through the safety valve 124 and the conduit 7 to the space below the piston 8 forcing the latter upwards. During this upward motion the press plate 20 remains closed for a while; but the rails 12 are taken along towards the top. When the pins 17 reach the lower oblique part of the groove 15, the racks 18 are shifted, respectively the locking sleeves 27 are rotated in such a way as to unlock the press plate. piston 8 the press plate 20 is taken along, separating the upper moulding die 33 from the lower die 58. Furthermore the stop surface 55 of the yoke 11 acts upon the extension part 53 whereby the lever 50 is swung towards the top and the ejection piston 43 by means of the lever 46 is shifted towards the front. Said piston 43 delivers a certain amount of moulding material to the funnel 56. Furthermore when the projections 66 of the press plate 20 act upon the nuts 67 present on the rods 65, the ejector 61 is lifted by means of the cross bar 64 and the support rod 62 and thereby ejects the finished die-cast piece. At the end of the upward stroke of the piston 8, the nut 113 fastened to the rod 112 acts upon the lever arm 111 whereby the control shaft 110 is rotated in such a way that the manually operated lever is moved back into its middle position M. Since by this also the slide valve 117 is moved back into its middle position, further movement of the piston 8 is halted and the die-casting machine is in readiness position for a further upward stroke.

The above described die-casting press can be used also for other purposes. Thus it may be employed as transfer press, Bakelite press or sheet metal press, in which cases merely the injection head has to be removed and corresponding additional parts have to be provided.

Furthermore instead of upright the press could also be built as horizontal press, in which construction the first press plunger would act in one direction and the second press plunger in the opposite direction.

It is to be understood that some the the details set forth in the described embodiment of my invention may 5 be altered or omitted without departing from the spirit of my invention as defined by the following claims:

I claim:

1. A press with hydraulically operated press plungers,

comprising upper and lower cylinder blocks, a plurality of columns connecting said cylinder blocks in spaced relation to each other, a first press plunger of large cross section and short stroke mounted in said lower cylinder block and a second press plunger of smaller cross section and longer stroke mounted in said upper cylinder block, said plungers acting in opposite directions, a press plate mounted on said columns, means operatively connecting said press plate to said second press plunger whereby said press plate is moved simultaneously by the second press plunger during a first part of its forward movement and means retaining said press plate in its furthermost position on the columns, while the second press plunger continues its further forward movement.

2. A die-casting press with hydraulically operated press plungers, comprising upper and lower cylinder blocks, a plurality of columns connecting said cylinder blocks in spaced relation to each other, a die comprising two halves, a first press plunger of large cross-section and short stroke carrying one half of the die mounted in said lower cylinder block, a second press plunger of At the further upward movement of the 6 v smaller cross-section and longer stroke carrying the second half of the die and the injection head mounted in said upper cylinder block, said press plungers acting in opposite directions, a press plate mounted on said columns, means operatively connecting said press 'plate to said second press plunger whereby said press plate is moved simultaneously by the second press plunger during a first part of its forward movement, means for retaining said press plate in fixed position on the columns while the second press plunger continues its further forward movement, and means for shifting said press plate to effect a closure of the die halves, whereby continued forward movement of the second press plunger eflects injection of material into the die.

3. A press according to claim 1, wherein said columns are provided with longitudinal grooves and splines and are surrounded by locking sleeves journalled in said press plate, said sleeves being provided on their inside with longitudinal grooves and splines and said sleeves are adapted to rotate out of a position, in which the splines of the sleeves correspond with the longitudinal grooves of the columns, into a position in which the splines of the sleeves engage the splines of the columns for the purpose of locking the press plate.

4. A press according to claim 3, in which the splines of the columns at the place where the press plate is to be retained in fixed relation with said columns are provided with external screw threads and the splines of the locking sleeves have internal screw threads, adapted to be brought into engagement with the external threads of the splines of the column at the fixed position of the press plate.

5. A press according to claim 3, wherein the locking sleeves are provided with external screw threads adapted to be screwed into internal threads of reception borings of the press plate in such a manner that at the mentioned rotation they are simultaneously moved in axial direction for the purpose of locking and unlocking said locking sleeves.

6. A press according to claim 3, wherein each of the said locking sleeves is provided with a toothed portion adapted to be engaged by a rack such that by shifting of the rack the locking sleeve can be rotated.

7. A press according to claim 3, wherein a rack is provided that carries a pin adapted to engage a groove of a rail connected with the second press plunger, which groove at its outer end follows a slanted course so that at the abutment of the press plate against a stop surface the rack is shifted and the locking sleeve is rotated.

8. A press according to claim 3, wherein two rails are adapted each to coact with a rack and each rack coacts with two of said locking sleeves and four sleeves are provided, so that a sleeve is adapted to be locked with each column.

9. A press according to claim 1, wherein said press plungers are movable in a vertical direction and wherein the first, lower press plunger is adapted to move upwardly from the bottom of the press towards the top thereof and the second upper press plunger from the top of the press towards the bottom therof.

10. A press according to claim 1, wherein a reversing slide valve is provided in a pressure fluid conduit leading to the cylinder of the upper press plunger, and said slide valve is connected with a hand-operable control shaft and a stop valve is provided in the pressure fluid conduit leading to the lower side of the upper press plunger in order to stop this press plunger together with the parts connected with it in any desired adjustment position.

11. A press according to claim 1, wherein a control cam is connected with the upper press plunger, and said cam is adapted to coact with a stop member which by means of a linkage and latches is in connection with a slide valve which under the action of the control cam upon the stop member is so shifted, that the pressure fluid a control valve for maintaining the pressure in the cylin- 1f) der of the'lower press plunger, so that that said valve is opened andthe lower press plunger is unloaded.

13. A press according to claim 1, wherein a control shaft is provided that controls the upward movement of the upper press plunger, so that when the press plunger has obtained its uppermost position, said shaft moves into its middle position, and a reversing slide valve is provided that occupies an ineffective position upon movement of said shaft into the middle position.

References Cited in the file of this patent UNITED STATES PATENTS Shaw Sept. 23, 1941 Gastrow Mar. 6, 1945 

